Stent retaining systems

ABSTRACT

A stent delivery system includes an expandable stent, a catheter, and a sheath. The expandable stent includes proximal and distal ends, and a first interlock structure. The catheter includes an elongated member having a second interlock structure displaceably arranged about an outer surface thereof for engaging the first interlock structure of the stent. The sheath is mounted on the elongated member and is positionable in a transport position in which the sheath covers the stent mounted on the elongated member and a deploy position in which the stent is exposed.

This application is a continuation of U.S. patent application Ser. No.13/364,772, filed Feb. 2, 2012, the entire content of which isincorporated herein by reference.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to a system for delivering an implant toa site in a body lumen. More particularly, the present disclosurerelates to a delivery system for a self-expandable implant such as astent.

2. Description of the Related Art

Stents are widely used for supporting a lumen structure in a patient'sbody. For example, stents may be used to maintain patency of a coronaryartery, other blood vessel, or other body lumen.

Commonly, stents are metal tubular structures. Stents are passed throughthe body lumen in a collapsed state. At the point of an obstruction orother deployment site in the body lumen, the stent is expanded to anexpanded diameter to support the lumen at the deployment site.

In certain designs, stents are open-celled tubes which are expanded byinflatable balloons at the deployment site. Other stents are so-called“self-expanding” stents. Self-expanding stents do not use balloons orother applications of force to cause the expansion of a stent in acollapsed state. An example of a self-expanding stent is a coilstructure which is secured to a stent delivery device under tension in acollapsed state. At the deployment site, the coil is released so thatthe coil can expand to its enlarged diameter. Other self-expandingstents are made of so-called shape-memory metals such as nitinol. Suchshape-memory stents experience a phase change at the elevatedtemperature of the human body. The phase change results in expansionfrom a collapsed state to an enlarged state.

A delivery technique for shape-memory alloy stents is to mount thecollapsed stent on a distal end of a stent delivery system. Such asystem would include an outer tubular member and an inner tubularmember. The inner and outer tubular members are axially slideablerelative to one another. The stent (in the collapsed state) is mountedsurrounding the inner tubular member at its distal end. The outertubular member (also called the outer sheath) surrounds the stent at thedistal end.

Prior to advancing the stent delivery system through the body lumen, aguide wire is first passed through the body lumen to the deploymentsite. The inner tube of the delivery system is hollow throughout itslength such that it can be advanced over the guide wire to thedeployment site.

The combined structure (i.e., stent mounted on stent delivery system) ispassed through the patient's lumen until the distal end of the deliverysystem arrives at the deployment site within the body lumen. Thedeployment system may include radiopaque markers to permit a physicianto visualize positioning of the stent under fluoroscopy prior todeployment.

At the deployment site, the outer sheath is retracted to expose thestent. The exposed stent is now free to expand within the body lumen.Following expansion of the stent, the inner tube is free to pass throughthe stent such that the delivery system can be removed through the bodylumen leaving the stent in place at the deployment site.

In prior art devices, the stent may prematurely deploy as the outer tubeis retracted. Namely, with the outer tube partially retracted, theexposed portion of the stent may expand resulting in the remainder ofthe stent being squeezed out of the outer tube. This can result in thestent being propelled distally beyond a desired deployment site. Also,once the stent is partially unsheathed, it is sometimes determined thatthe stent placement needs to be adjusted. With existing systems, this isdifficult since the stent has a tendency to force itself out of thesheath thereby making adjustments difficult.

It would be advantageous to provide a system that retains the stent onthe catheter even when a majority of the stent has been exposed byretraction of the sheath and that allows a stent to be re-sheathed evenafter a majority of the stent has been exposed by retraction of thesheath.

The present disclosure provides improved structures for self-expandableimplant delivery systems such as stent delivery systems.

SUMMARY

In accordance with an aspect of the present disclosure, a stent deliverysystem includes an expandable stent, a catheter, and a sheath. Theexpandable stent includes proximal and distal ends, and a firstinterlock structure. The catheter includes an elongated member having asecond interlock structure displaceably arranged about an outer surfacethereof for engaging the first interlock structure of the stent. Thesheath is mounted on the elongated member and is positionable in atransport position in which the sheath covers the stent mounted on theelongated member and a deploy position in which the stent is exposed.

In embodiments, the second interlock structure is freely moveable alonga longitudinal length of the elongated member. In other embodiments, themovement of the second interlock structure is limited over apredetermined length of the elongated member.

The second interlock structure may be unattached to the elongatedmember. In some embodiments, the second interlock structure may beattached to an intermediate tube disposed between the elongated memberof the catheter and the sheath. In other embodiments, the secondinterlock structure may be attached to the elongated member by aflexible structure, such as a spring, that allows the second interlockstructure to move a predetermined distance along the elongated member.

The second interlock structure may be positioned on a floating retainingring. The floating retaining ring may be a continuous or discontinuousring extending completely or partially around the elongated member.

In accordance with another aspect of the present disclosure, a stentdelivery system includes an expandable stent, a catheter, and a sheath.The expandable stent includes a plurality of interconnected cellsextending between a proximal end and a distal end. The catheter includesan elongated member having a stent mounting location and includes adeformable retaining ring disposed around the elongated member. Thesheath is mounted on the elongated member and is positionable in atransport position in which the sheath covers the stent mounted on theelongated member and a deploy position in which the stent is exposed.The deformable retaining ring defines a diameter that is larger than adiameter of the sheath such that when the sheath is in the transportposition an outer edge of the deformable retaining ring overlies theproximal end of the stent. The deformable retaining ring may befabricated from a foam or an elastomer. The deformable retaining ringmay be a continuous or discontinuous ring extending completely orpartially around the elongated member.

In accordance with yet another aspect of the present disclosure, a stentdelivery system includes an expandable stent, a catheter, and a sheath.The expandable stent includes a plurality of interconnected cellsextending between a proximal end and a distal end. The catheter includesan elongated member having a stent mounting location including acompressible material. The sheath is mounted on the elongated member andis positionable in a transport position in which the sheath covers thestent mounted on the elongated member such that the cells of the stentare pressed into and capture the compressible material, and a deployposition in which the stent is exposed. The compressible material may bea foam or an elastomer. In embodiments, the stent attachment location ofthe elongated member may include fibers extending radially therefrom,such that when the sheath is in the transport position, the fibers arecaptured by the cells of the stent.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will be better appreciated byreference to the drawings wherein:

FIG. 1 is a side elevation view of a stent delivery system according toprinciples of the present disclosure;

FIG. 2A is an enlarged cross-sectional view of detail A of FIG. 1 withthe stent in a compressed orientation;

FIG. 2B is an enlarged cross-sectional view of detail A of FIG. 1 withthe stent in a deployed (i.e., expanded) orientation;

FIG. 3 is an enlarged cross-sectional view of detail B of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of detail C;

FIG. 5 is a cross-sectional view of the inner and outer tubular membersof the stent delivery system of FIG. 1 taken along section line 5-5 ofFIG. 3;

FIG. 6A is a plan view of a first stent having an interlock structurethat interlocks with an interlock structure of a collar of an innertube, the stent and a collar are shown cut longitudinally and laid flatwith an axial separation between the stent proximal end and the collar;

FIG. 6B is the view of FIG. 6A with the stent proximal end and collarshown interlocked;

FIG. 6C is an end view of the stent of FIGS. 6A and 6B in its tubularconfiguration;

FIG. 7A is a laid flat, plan view of a stent having an interlockstructure that interlocks with an interlock structure of an inner tubein accordance with an embodiment of the present disclosure;

FIG. 7B is a laid flat, plan view of a stent having an interlockstructure that interlocks with an interlock structure of a retainingring of an inner tube in accordance with another embodiment of thepresent disclosure;

FIG. 8 is a laid flat, plan view of a stent having an interlockstructure that interlocks with an interlock structure of an inner tubein accordance with yet another embodiment of the present disclosure;

FIG. 9A is a laid flat, plan view of a stent having an interlockstructure that interlocks with an interlock structure of an inner tubein accordance with an embodiment of the present disclosure;

FIG. 9B is the view of FIG. 9A with the mating structures of the stentand inner tube shown interlocked;

FIG. 9C is a laid flat, plan view of a stent having radiopaque markersand an interlock structure that interlocks with an interlock structureof an inner tube in accordance with another embodiment of the presentdisclosure;

FIG. 10A is a laid flat, plan view of a stent having an interlockstructure that interlocks with an interlock structure of an inner tubein accordance with an embodiment of the present disclosure;

FIG. 10B is an enlarged side view of detail D of FIG. 10A;

FIG. 10C is a side plan view of the interlock structure of FIG. 10Bshown interlocked;

FIGS. 11A and 11B are perspective view of a retaining structure for theinterlock structure of the inner tube in accordance with embodiments ofthe present disclosure;

FIG. 11C is an end view of a retaining structure for the interlockstructure of the inner tube in accordance with embodiments of thepresent disclosure;

FIG. 12A is a side view of a floating interlock structure of an innertube in accordance with an embodiment of the present disclosure;

FIG. 12B is a side view of a floating interlock structure of an innertube in accordance with another embodiment of the present disclosure;

FIG. 12C is a side view of a floating interlock structure of an innertube in accordance with yet another embodiment of the presentdisclosure;

FIG. 13A is a cross-sectional view of a stent having an interlockstructure interlocked with an interlock structure of an inner tube inaccordance with an embodiment of the present disclosure;

FIG. 13B is a cross-sectional view of an interlock structure of theinner tube in accordance with another embodiment of the presentdisclosure;

FIG. 14A is a perspective view of an interlock structure of an innertube in accordance with an embodiment of the present disclosure;

FIG. 14B is a cross-sectional view of a stent having an interlockstructure interlocked with the interlock structure of FIG. 14A;

FIGS. 15A and 15B are schematic cross-sectional illustrations of aninterlock structure of a stent and an inner tube with the stentpositioned in a compressed and expanded state, respectively, inaccordance with an embodiment of the present disclosure;

FIG. 16A is a schematic cross-sectional illustration of an interlockstructure of an inner tube interlocked with a stent in accordance withan embodiment of the present disclosure; and

FIG. 16B is a schematic cross-sectional illustration of an interlockstructure of an inner tube in accordance with another embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Various exemplary embodiments of the present disclosure will bediscussed hereinbelow in terms of a stent delivery system equipped withan interlock configuration that constrains relative axial movement of astent about an inner tube until after the outer tube has been fullyretracted. It should be understood that a variety of stent deliverysystems may be utilized with the embodiments of the interlockconfiguration of the present disclosure.

Embodiments of the presently disclosed stent delivery system will now bedescribed in detail with reference to the drawing figures wherein likereference numerals identify similar or identical elements. In thefollowing discussion, the terms “proximal” and “trailing” may beemployed interchangeably, and should be understood as referring to theportion of a structure that is closer to a clinician during proper use.The terms “distal” and “leading” may also be employed interchangeably,and should be understood as referring to the portion of a structure thatis further from the clinician during proper use. As used herein, theterm “patient” should be understood as referring to a human subject orother animal, and the term “clinician” should be understood as referringto a doctor, nurse or other care provider and may include supportpersonnel.

With initial references to FIGS. 1-4, an exemplary stent delivery system10 is shown. The stent delivery system 10 is for delivery of a stent 12to a deployment site in a body lumen of a patient's body. By way ofnon-limiting, representative example, the stent 12 may be aself-expanding, open-celled, tubular stent having a construction such asthat shown in U.S. Pat. No. 6,132,461, which is hereby incorporated byreference, and formed of a self-expanding, shape-memory or superelasticmetal such as nitinol, or the like. The stent 12 may also be a coilstent, any other self-expanding stent, or a balloon expandable stentsuch as that shown in U.S. Pat. No. 6,827,732, which is herebyincorporated by reference. The stent 12 includes a proximal end 12 a anda distal end 12 b. Another representative stent is shown in U.S. Pat.No. 6,558,415, which is hereby incorporated by reference.

The stent 12 is carried on the stent delivery system 10 in a collapsed(or reduced diameter) state as shown in FIG. 2A. Upon release of thestent 12 from the stent delivery system 10 (as will be described), thestent 12 expands to an enlarged diameter (see FIG. 2B) to abut againstthe walls of the patient's lumen in order to support patency of thelumen.

The stent delivery system 10 includes an inner tubular member 14 (i.e.,also referred to as an elongated member) and an outer tubular member 16.Both of the inner and outer tubular members 14 and 16 extend fromproximal ends 14 a, 16 a to distal ends 14 b, 16 b.

The outer tubular member 16 is sized to be axially advanced through thepatient's body lumen. In embodiments, the tubular member 16 issufficiently long for the distal end 16 b to be placed near thedeployment site in the patient's body lumen with the proximal end 16 aremaining external to the patient's body for manipulation by aclinician. By way of example, the outer tubular member 16 (also referredto as a sheath) may be a braid-reinforced polyester of tubularconstruction to resist kinking and to transmit axial forces along thelength of the sheath 16. The outer tubular member 16 may be of widelyvarying construction to permit varying degrees of flexibility of theouter tubular member 16 along its length.

As shown in FIG. 3, the proximal end 16 a of the outer tubular member 16is bonded to a manifold housing 20. The manifold housing 20 isthreadedly connected to a lock housing 22. A strain relief jacket 24 isconnected to the manifold housing 20 and surrounds the outer tubularmember 16 to provide strain relief for the outer tubular member 16.

In embodiments, the inner tubular member 14 is formed of nylon but maybe constructed of any suitable material. As shown in FIG. 2B, the innertubular member 14 defines a stent attachment location 26. The innertubular member 14 also includes radiopaque markers 27, 28 that areattached to an outer surface of the inner tubular member 14 (e.g., bytechniques such as adhesive, heat fusion, interference fit, or othertechniques). The attachment location 26 is positioned between theradiopaque markers 27, 28. The radiopaque markers 27, 28 permit aclinician to accurately determine the position of the stent attachmentlocation 26 within the patient's lumen under fluoroscopic visualization.As will be described later in the specification, in some embodiments, atleast one of the markers 27, 28 forms a collar including a geometry thatinterlocks with the stent 12 to prevent axial movement of the stent 12relative to the inner tubular member during transport and deployment ofthe stent 12. In other embodiments, markers 27, 28 are positioned on theproximal end 12 a and/or distal end 12 b of the stent 12.

A tapered and flexible distal tip member 30 is secured to the distal end14 b of the inner tubular member 14. The highly flexible distal tipmember 30 permits advancement of the stent deployment system 10 throughthe patient's lumen and minimizes trauma to the walls of the patient'slumen.

As best shown in FIGS. 3 and 4, the inner tube 14 passes through boththe manifold housing 20 and lock housing 22. A stainless steel jacket 32surrounds and is bonded to the inner tubular member 14. At the innertube proximal end 14 a, a port housing 34 is bonded to the stainlesssteel jacket 32. The port housing 34 has a tapered bore 36 aligned withan inner lumen 38 of the tubular member 14. The inner lumen 38 extendscompletely through the inner tubular member 14 so that the entiredelivery system 10 can be passed over a guide wire (not shown) initiallypositioned within the patient's lumen. Opposing surfaces of the innerand outer tubular members 14 and 16, define a first lumen 40 (best seenin FIG. 5). As described in U.S. Pat. No. 6,623,491, which is herebyincorporated by reference, splines 18 can be provided between the innerand outer tubular members 14 and 16.

As shown in FIG. 3, the manifold housing 20 carries an admission port 42for injecting a contrast media into the interior of the manifold housing20. The interior of the manifold housing 20 is in fluid flowcommunication with the first lumen 40. Discharge ports 41 (shown inFIGS. 2A and 2B) are formed through the outer tubular member 16 topermit contrast media to flow from the first lumen 40 into the patient'sbody lumen.

As shown in FIG. 3, an O-ring 44 surrounds the stainless steel jacket 32between the manifold housing 20 and lock housing 22. Upon threadedconnection of the manifold housing 20 to the lock housing 22, the O-ring44 compresses against the stainless steel jacket 32 in sealingengagement to prevent contrast media from flowing in any path other thanthrough the first lumen 40.

As shown in FIGS. 1 and 3, the lock housing 22 carries a threadedlocking member (or lock nut) 46 which can be turned to abut thestainless steel jacket 32. The lock nut 46 can be released to free thestainless steel jacket to move axially. According, when the lock nut 46engages the jacket 32, the jacket 32 (and attached inner tubular member14) cannot move relative to the lock housing 22, manifold housing 20, orthe outer tubular member 16. Upon release of the lock nut 46, the innertubular member 14 and outer tubular member 16 are free to slide axiallyrelative to one another between a transport position and a deployposition.

First and second handles 48, 50 are secured to the lock housing 22 andjacket 32, respectively. In the transport position (shown in FIG. 2A),the handles 48, 50 are spaced apart and the distal end of the outertubular member 16 forms a sheath that covers the stent attachmentlocation 26 to prevent premature deployment of the stent 12. When thehandle 48 is pulled rearwardly toward the handle 50, the outer tubularmember 16 slides rearwardly or proximally relative to the inner tubularmember 14. In embodiments, the outer tubular member 16 slides rearwardlya distance sufficient to fully expose the stent attachment location 26and permit the stent 12 to freely expand toward its fully expandeddiameter (see FIG. 2B). After such expansion, the stent delivery system10 can be proximally withdrawn through the expanded stent 12 andremoved.

As shown in FIG. 3, the first handle 48 is rotatably mounted on a flange22 a of the lock housing 22. The first handle 48 surrounds the stainlesssteel jacket 32 and is freely rotatable about the longitudinal axis ofthe jacket 32 and freely rotatable about the flange 22 a. The firsthandle 48 is axially affixed to the lock housing 22 such that axialforces applied to the first handle 48 are transmitted through the lockhousing 22 and manifold housing 20 to the outer tubular member 16 toaxially move the outer tubular 16. However, rotary action of the firsthandle 48 about the axis of the stainless steel jacket 32 is nottransmitted to the housings 20, 22 or to the outer tubular member 16 byreason of the free rotation of the first handle 48 on flange 22 a.

As shown in FIG. 4, the second handle 50 is mounted on an anchor 52 thatis bonded to the stainless steel jacket 32 through any suitable means(such as by use of adhesives). The anchor 52 includes a flange 52 a thatis radial to the axis of the stainless steel jacket 32. The secondhandle 50 is mounted on the flange 52 a and is free to rotate on theanchor 52 about the axis of the stainless steel jacket 32. However,axial forces applied to the handle 50 are transmitted to the stainlesssteel jacket 32 which, being bonded to the inner tubular member 14,results in axial movement of the inner tubular member 14.

With the handle construction described above, relative axial movementbetween the handles 48, 50 results in relative axial movement betweenthe inner and outer tubular members 14, 16. Rotational movement ofeither of the handles 48, 50 does not affect rotational positioning ofthe inner or outer tubular members 14, 16 and does not affect axialpositioning of the inner and outer tubes 14, 16.

The free rotation of the handles 48, 50 results in ease of use for aclinician who may position his or her hands as desired without fear ofinterfering with any axial positioning of the inner and outer tubularmembers 14, 16. The spacing between the handles 48, 50 is equal to thestroke between the transport position and the deploy position of thetubular members 14, 16. As a result, the spacing permits a clinician tohave ready visual indication of the relative axial positioning betweenthe inner and outer tubular members 14, 16. This relative axialpositioning can be fixed by engaging the lock nut 46. In any suchpositioning, contrast media can be injected through the admission port42 into the chamber 40 with the contrast media flowing out of the sideports 41 into the body lumen to permit visualization under fluoroscopy.

With stent deployment systems having premounted stents of various axiallengths, the positioning of the second handle 50 on the stainless steeljacket 32 can be selected at time of assembly so that a spacing S (seeFIG. 1) between the handles 48, 50 corresponds to the length of thestent 12 carried on the stent deployment system. For example, in anembodiment, the spacing S is about 10 millimeters longer than thedeployed length of the stent. Accordingly, a clinician will know thatthe outer tubular member 16 has been fully retracted when the handles48, 50 have been pushed completely together to completely release thestent 12. Also, the freely rotatable handles 48, 50 are easy to holdfrom any angle without slippage. The lock nut 46 ensures that the stent12 will not deploy prematurely.

A concern with existing delivery systems for self-expanding stents iscontrol of stent delivery. For example, due to their elasticcharacteristics, self-expanding stents have a tendency to propelthemselves axially outwardly from their restraining sheaths before thesheaths have been completely retracted. When this occurs, control ofstent placement is compromised since the stent may overshoot the desireddeployment site. Further, once the stent has been completely deployed,subsequent adjustment of the stent deployment location can be difficultbecause re-sheathing typically cannot be readily accomplished.

To address the above concerns, the delivery system 10 is equipped withan interlock configuration that constrains relative axial movementbetween the stent 12 and the inner tube 14 until after the sheath 16 hasbeen fully retracted. For example, when the stent 12 is mounted on theinner tube 14 and restrained in the compressed orientation by the sheath16 as shown in FIG. 2A, a first interlock structure 82 (e.g., acontinuous ring as shown in FIG. 2A) located at the proximal end of thestent 12 interlocks with a second interlock structure 84 (e.g., aplurality of protuberances as shown in FIG. 2A) defined by the proximalmarker 27 (also referred to as a collar). The interlock geometriesremain interlocked to constrain axial movement of the stent 12 untilafter the sheath 12 has been retracted beyond a predetermined location(e.g., the proximal-most end 12 a of the stent 12). When the sheath 12has been retracted beyond the predetermined location, the firstinterlock structure 82 of the stent 12 is allowed to expand. As thestent 12 expands, the first interlock structure 82 of the stent 12disengages from the second interlock structure 84 of the marker 27thereby allowing the inner tube 14 of the catheter to be moved axiallyrelative to the stent 12 without interference from the first and secondinterlock structures 82, 84.

FIGS. 6A and 6B illustrate the proximal end 12 a of the stent 12 inrelation to the marker 27 located at the proximal end of the attachmentlocation 26. In FIGS. 6A and 6B, the stent 12 and the marker 27 havebeen cut longitudinally and laid flat. The stent 12 has a length L and acircumference C. In FIG. 6A, the marker 27 and the stent 12 are showndisengaged from one another. In FIG. 6B marker 27 and the stent 12 areshown interlocked.

Referring to FIG. 6A, the stent 12 includes a plurality of struts 86(i.e., reinforcing members). A number of the plurality of struts, e.g.twelve, define a cell 17 (also shown in FIG. 2B). The stent 12 is madeup of a plurality of interconnected cells 17. Still referring to FIG.6A, each cell has a compressed or collapsed cell length Lc. At leastsome of the struts 86 of the cells 17 have free terminal ends thatdefine the proximal and distal ends 12 a and 12 b of the stent 12. Firstinterlock structures 82 (i.e., keys) are provided at the free terminalends of the struts 86. As shown in FIG. 6A, the first interlockstructures 82 include enlargements in the form of circular projectionsthat extend a distance d from the free terminal ends of the struts 86.In embodiments, the distance d that the first interlock structures 82extends from the free terminal ends of the struts 86 is less than thecollapsed cell length Lc of the cells 17. Thus, the first interlockstructures 82 are within at most one collapsed cell length Lc of thecells 17.

The circular projections of the first interlock structures 82 includeinterlock portions 88 that project outwardly from the struts 86 in acircumferential direction (i.e., in a direction coinciding with thecircumference C of the stent 12). The interlock portions 88 includeinterlock surfaces 90 that face in an axial direction. The phrase “facein an axial direction” will be understood to mean that least a vectorcomponent of the surface 90 is perpendicular with respect to alongitudinal axis A-A of the stent 12. Thus, the surface 90 need not becompletely perpendicular relative to the longitudinal axis of the stent12 to be construed as facing in an axial direction. In other words, asurface aligned at oblique angle relative to the longitudinal axis ofthe stent 12 shall also be construed as facing in an axial directionsince such surface has a vector component that is perpendicular relativeto the longitudinal axis of the stent.

As best shown schematically in FIG. 6C, the first interlock structures82 are positioned within a region defined between an inner diameter D1and an outer diameter D2 of the stent 12. In embodiments, at leastportions of the interlock surfaces 90 are located within 5 millimetersof the proximal end 12 a of the stent 12. In some embodiments, at leastportions of the interlock surfaces 90 are located within 3 millimetersof the proximal end 12 a of the stent 12. In yet other embodiments, atleast portions of the interlock surfaces 90 are located within 2millimeters of the proximal end 12 a of the stent 12.

Still referring to FIGS. 6A and 6B, the radiopaque marker 27 has anaxial distal edge 29 facing the proximal end 12 a of stent 12. Secondinterlock structures 84 (i.e., discontinuous sockets, openings, keyways,etc.) are at least partially defined by the radiopaque marker 27. Eachof the second interlock structures 84 includes interlock surfaces 92that face in an axial direction. The second interlock structures 84 areconfigured to have a complementary mating geometry with respect to thefirst interlock structures 82 of the stent 12. For example, similar tothe first interlock structures 82, the second interlock structures 84are shown having generally rounded or circular shapes. By“complementary”, it is meant that the mating geometry of the interlockconfiguration need not have identical or substantially identicalcomplementary shapes, but rather, to provide an interlock, it is onlynecessary for a portion of the first interlock structure 82 to bereceived in the second interlock structure 84, or vice versa, such thatmechanical interference or overlap between the first and secondinterlock structures 82, 84 prevents the interlocks from being axiallyseparated.

The geometry of the second interlock structures 84 is selected to matewith the predetermined geometry of the proximal end 12 a of the stent 12such that the stent 12 and the marker 27 can be axially coupled orinterlocked when the stent 12 is compressed at the mounting location 26.When the first and second interlock structures 82 and 84 areinterlocked, the interlock surfaces 90 and 92 oppose andcircumferentially overlap one another (see FIG. 6B) such that the stent12 is restricted from distal movement relative to the marker 27.

With the specific embodiment shown, the stent 12 and collar 27 arerotary coupled such that the stent 12 and collar 27 are restricted fromrelative rotary motion (i.e., about axis A-A) when the stent 12 is inthe collapsed state. The predetermined stent geometry of the firstinterlock structures 82 and the complementary mating geometry of thesecond interlock structures 84 of the collar 27 do not restrict relativeradial motion. Namely, as the self-expanding stent 12 expands radially,the first interlock structures 82 are free to radially move out of thesecond interlock structures 84. After such motion, the stent 12 is nolonger coupled to the collar 27 and the stent 12 and collar 27 are freeto move axially, radially, or transversely to one another.

With the embodiment thus described, the mating features of the stent 12and collar 27 prevent premature discharge of the stent 12 from a stentattachment location 26. As the outer sheath 16 is retracted, the sheathdistal end 16 b exposes the distal end 12 b of the stent 12. At thispoint, the exposed distal end 12 b of the stent 12 is free for limitedexpansion restrained by the remainder of the stent 12 being covered bythe sheath 16 and by the attachment of the stent proximal end 12 a tothe proximal radiopaque marker 27.

Further retraction of the sheath 16, permits still further expansion ofthe stent 12. As the sheath distal end 12 b approaches the stentproximal end 12 a, the expansion of the stent material tends to urge thestent 12 to squeeze out of the small portion of the sheath 16 nowcovering the stent 12. However, this propensity is overcome by theattachment of the stent proximal end 12 a to the collar 27 since anysuch ejection of the stent 12 would require axial separation of thestent 12 and collar 27. Such movement is prevented by the firstinterlock structures 82 and the second interlock structures 84.

Therefore, as long as any portion of the sheath 16 overlies the firstand second interlock structures 82 and 84, the proximal end 12 a of thestent 12 cannot expand and cannot axially move away from the collar 27.Accordingly, the stent 12 is not released from the attachment location26 until a clinician has fully retracted the sheath 16 with the sheathdistal end 16 b retracted proximal to the proximal end of stentattachment location 26. The sheath distal end 16 b is provided with aradiopaque marker 16 b′ (shown in FIGS. 2A and 2B) to permitvisualization of the relative position of the sheath distal end 12 b andthe radiopaque markers 27, 28 of the stent attachment location 26.

With the structure and operation thus described, a clinician has greatercontrol of the release of the stent 12 and more accurate stentpositioning is attained. As long as even a small portion of the sheath16 is not fully retracted (e.g., at least 1 mm extends distally to theproximal end 12 a of the stent 12) the axial position of the stent 12may be adjusted by advancing or retracting the inner tubular member 14.Also, as long as a small portion of the sheath 16 remains covered by thesheath 16 (e.g., at least 1 mm), the stent 12 may be readily re-sheathedby moving the sheath 16 in a distal direction.

In the embodiment of FIGS. 6A and 6B, the pattern and shape of the firstinterlock structures 82 and the second interlock structures 84 aresymmetrical about the stent axis A-A. As a result, the stent 12 can beaffixed to the collar 27 in any one of a plurality of rotary alignmentsabout axis A-A. It will be appreciated that the pattern and shape ofinterlock structures 82, 84 may vary such that the stent 112 can only beaffixed to the collar 27 in a limited or unique mating structure.

Further, the embodiment of FIGS. 6A and 6B shows that the interlockbetween the stent 12 and the tube 14 is provided at the proximal end 12a of the stent 12 b. It will be appreciated that for certainembodiments, the interlock between the inner tube 14 and the stent 12can be provided at the distal end 12 b of the stent 12 (e.g., for adistally retractable sheath). Moreover, while the embodiment of FIGS. 6Aand 6B shows interlock structures provided at all of the proximal endsof the struts 86, the interlock structures of the present disclosure arenot so limited. For example, in some embodiments, only some of thestruts 86 may include interlock structures. While in certain embodimentsit may be desirable to use only one interlock structure at the end ofthe stent 12, in other embodiments, it may be desirable to use at leasttwo separate/discrete interlock structures uniformly spaced about thecircumference of the stent. In yet other embodiments, it may bedesirable to use at least 4 separate/discrete interlock structures thatmay be uniformly spaced about the circumference of the stent.

The collar 27 may be provided with indicia to indicate to a clinicianthe position of the collar 27 (and hence the stent 12) when thecombination is in a patient's vessel and is being visualized underfluoroscopy. In the embodiment of FIGS. 6A and 6B, the indicia is shownas cutouts 15 in the collar 27. Other configurations of indicia on orproximal to the collar 27 are envisioned, such as those described inU.S. Pat. No. 6,623,518, which is hereby incorporated by reference.

As described above, the interlock structure 84 of the inner tube 14 isprovided on the proximal radiopaque marker 27. It will be appreciatedthat the interlock structures 84 need not be the same element as theradiopaque marker 27 but could be a separate part. As a separate part,the interlock structures 84 could be integrally formed with, or joinedto, the inner tube 14, connected to the outer surface of the inner tube14 by conventional techniques (e.g., adhesive, fasteners, fusionbonding, etc.), or be connected to the outer surface of the inner tube14 by one or more intermediate members (e.g., a retaining ring).

FIG. 7A illustrates second interlock structures 84′ that include aplurality of protuberances 85′ separate from collar 27′. Protuberances85′ are provided on the inner tube and extend radially outward from theinner tube. Protuberances 85′ are positioned distal to the collar 27′.Protuberances 85′ may be formed from metal, polymer, or other materialsand may be fabricated as part of the inner tube (e.g., molded, stamped,etc.) or as separate pieces. In embodiments, protuberances 85′ may bepart of a single disk-like component built into the inner tube. FIG. 7Billustrates an embodiment of the second interlock structures 84′disposed on a retaining ring 89′ joined to an outer surface of the innertube distal to the collar 27′. It will be appreciated that inembodiments utilizing an interlock structure that is separate from thecollar, the collar may be omitted and a radiopaque marker may beprovided on the interlock structures themselves, such as onprotuberances 85″.

FIG. 8 illustrates second interlock structures 84″ that are formed ofprotuberances 85″ in combination with the collar 27″. Second interlockstructure 84″ includes interlock surfaces 92″ defined by surfaces of theprotuberances 85″ that face in an axial direction. Distal edge 29″ ofthe collar 27″ prevents the movement of the stent 12 proximally and aidsin preventing the interlocks 82′, 84′ from being axially separated.

FIGS. 9A and 9B illustrate an embodiment of a stent 112 including firstinterlock structures 182 in the form of circular openings definedthrough enlarged strut ends of the stent 112. The first interlockstructures 182 include distally facing interlock surfaces 190 and aresized to receive second interlock structures 184 in the form ofcylindrical posts, pins, or pegs. The posts are connected to the outersurface of the inner tube 14 (e.g., integrally or otherwise), oralternatively, may be connected to a collar or retaining ring. The postsdefine proximally facing interlock surfaces 192. When the first andsecond interlock structures 182 and 184 are coupled as shown in FIG. 9B,the surfaces 190 and 192 engage each other to prevent distal movement ofthe stent 112 relative to the posts.

FIG. 9C illustrates an embodiment of a stent 112′ where radiopaquemarkers 127′ are positioned on the proximal end 112 a′ of the stent112′. Radiopaque markers 127′ include enlargements in the form ofcircular projections that extend from the free terminal ends of thefirst interlock structures 182′. It will be appreciated that theradiopaque markers 127′ may be of any shape or size.

FIGS. 10A-10C illustrate an embodiment of a stent 212 and inner tube 214having another interlock configuration. Inner tube 214 has secondinterlock structures 284 in the form of slots including proximallyfacing interlock surfaces 292. The slots are sized to receive the firstinterlock structures 282 of the stent 212. The first interlockstructures 282 are posts extending from the terminal ends of the stent212 and include distally facing interlock surfaces 290. The firstinterlock structures 282 are fabricated from a shape memory or superalloy material that include a first position that is biased to extendradially outward from the longitudinal axis of the stent 212, asillustrated in FIG. 10B. The first interlock structures 282 are forcedinto a second position when the stent 212 is restrained in thecompressed orientation by the sheath 216, as shown in FIG. 10C, tocouple the first and second interlock structures 282, 284.

When the first and second interlock structures 282, 284 are coupled, thesurfaces 290 and 292 engage each other to prevent distal movement of thestent 212 relative to the posts. As long as any portion of the sheath216 overlies the first and second interlock structures 282, 284, theproximal end 212 a of the stent 212 cannot expand and cannot axiallymove away from the second interlock structure 284. Accordingly, thestent 212 is not released from the stent attachment location 226 until aclinician has fully retracted the sheath 216 with the sheath distal end216 b retracted proximal to the proximal end of stent attachmentlocation 226. Similar to the embodiments described above, it will beappreciated that the second interlock structures 284 may alternativelybe provided in a collar (not shown) or retaining ring (not shown).

While the collar and/or retaining ring to which the second interlockstructures may be attached is illustrated as a continuous structureencircling the inner tube, it will be appreciated that the collar and/orretaining ring may assume a variety of shapes. In embodiments, such asthose shown in FIGS. 11A-11C, the collar 327 may define a gap 325between free ends 321 and 323 (FIG. 11A), the free ends 321′ and 323′ ofcollar 327′ may overlap (FIG. 11B), or the collar 327″ may include twoor more separate ring sectors 327 a″ and 327 b″ (FIG. 11C). While FIGS.11A-11C illustrate embodiments of a collar having a discontinuousstructure that may be positioned about the inner tube, it will beunderstood that the same or similar structure may be provided in aretaining ring.

The collar and/or retaining ring may be unattached to the inner tubesuch that the retaining ring may float, longitudinally move, orotherwise be displaceably arranged along the inner tube. FIG. 12Aillustrates an embodiment of the second interlock structure 494 of aninner tube 414 positioned in a floating retaining ring 489. Floatingretaining ring 489 includes interlock structure complementary to theinterlock structure 82 of a stent 12 (e.g., FIG. 2A). It will beappreciated that any of the interlock structures described above may beproviding on a floating retaining ring 489. Likewise, it will beappreciated that the discontinuous collar/retaining ring configurationsdescribed above may also be displaceably arranged about the inner tube.

FIG. 12B illustrates an embodiment of a floating retaining ring 489′having another floating configuration. Floating retaining ring 489′ isattached at an end of an intermediate tube 419′ disposed between theinner tube 414′ and the sheath of the stent delivery system. Thefloating retaining ring 489′ is free to move with intermediate tube 419′along inner tube 414′.

FIG. 12C illustrate another embodiment of a floating retaining ring 489″that is unattached to the inner tube 414′, but attached to collar 427″by a flexible or elastic structure, such as spring 491′, that allows thefloating retaining ring 489″ to move between a compressed state in whichthe floating retaining ring 489′ abuts the collar 427″ and a stretchedstate extending a predetermined distance from the collar 427′ forlimited movement of the floating retaining ring 489″ along the innertube 414″.

Referring again to FIG. 5, splines 18 are radially projecting and extendat least partially along the length of the inner tubular member 14. Inembodiments, splines 18 extend substantially the entire axial length ofthe inner tubular member 14. The radial dimension and axial length ofeach of the splines 18 is identical and, in embodiments, all splines 18have a continuous uninterrupted length. However, it will be appreciatedthat the radial dimensions need not be identical and the splines 18 neednot have an uninterrupted length. Instead, the splines 18 are an exampleof an embodiment of a spacer member used to maintain a spacing betweenthe outer tubular member 16 and inner tubular member 14.

The spacer member 18 keeps the inner tubular member 14 in concentricalignment with the outer tubular member 16. This permits the use of avery small diameter inner tubular member 14 relative to the diameter ofthe outer tubular member 16 to increase the volume of the first lumen40. This reduces any impediment to flow of contrast media through thefirst lumen 40 and increases the volume of contrast media within thefirst lumen. By reason of the splines 18, the inner tubular member 14cannot bend relative to the outer tubular member 16, and since thesplines 18 contact the outer tubular member 16 only at small surfaceareas along the length, very small friction results from sliding motionbetween the inner and outer tubular members 14, 16.

With reference now to FIG. 13A, in conjunction with FIG. 5, splines 18are may be provided on the stent attachment location 26 of the innertube 14, in embodiments, distal to the proximal radiopaque marker 27. Insome embodiments, the splines 18 are adjacent to the proximal radiopaquemarker 27 or bonded thereto. Splines 18 are dimensioned to be receivedwithin cells 17 of stent 12 such that the splines 18 form the secondinterlocking structure of inner tube 14 and the cells 17 form the firstinterlocking structures of the stent 12. Splines 18 define axiallyfacing interlock surfaces (not shown) that face in a proximal directionand cells 17 define axially facing interlock surfaces 90 that face in adistal direction. When the splines 18 and cells 17 are interlocked, theinterlocks prevent the stent 12 from being axially withdrawn from thesplines 18. Upon expansion of the stent 12, the cells 17 disengage thesplines 18 thereby allowing the inner tube 14 of the catheter to bemoved axially relative to the stent 12.

FIG. 13B illustrates an embodiment of the splines 18′ including notches18 a′ formed in the proximal end of the splines 18′ to further preventradial expansion and thus, axial movement of the stent 12 until thestent 12 has been fully unsheathed by the outer tube 16.

FIGS. 14A and 14B illustrate an embodiment of an inner tube 514 havinganother interlock configuration. Retaining ring 589 is positioned oninner tube 514 and includes projections 589 a extending radially outwardfrom the inner tube 514. Retaining ring 589 is formed of a soft plastic,rubber, or other materials with elastomeric properties that may betemporary deform upon the application of pressure thereto. Asillustrated in FIG. 14B, retaining ring 589 is positioned on the innertube 514 with projections 589 a extending through cells 17 of the stent12 such that the projections 589 a form the second interlockingstructure of inner tube 14 and the cells 17 form the first interlockingstructures of the stent 12. Projections 589 a bend and overlie the stent12 upon compression by sheath 16. When the sheath 16 is retracted toexpose stent 12, the cells 17 of the stent 12 are released from theprojections 589 a of the retaining ring 589.

FIGS. 15A and 15B illustrate another embodiment of a deformableretaining ring 689. Retaining ring 689 is illustrated as a disk disposedabout the inner tube 14. Retaining ring 689 is formed from acompressible material such as foam or an elastomer such as a softurethane gel, silicone gel, thermoplastic elastomer, and the like. Thediameter of the compressible retaining ring 689 is larger than thediameter of the outer tube 16. When the outer tube 16 is positioned overthe stent 612, retaining ring 689 is deformed such that the outer radialedge 689 a overlies and is pressed into the proximal end 612 a of thestent 612, as illustrated in FIG. 15A. When the outer tube 16 isretracted the outer radial edge 689 a of the retaining ring 689 followsthe direction of the sheath to unveil the proximal end 612 a of thestent 612 so that the stent 612 can expand, as illustrated in FIG. 15B.

FIG. 16A illustrate an embodiment of an inner tube having an interlockstructure. Inner tube 714 may be formed or coated with a compressiblematerial 714 a such as a foam or elastomer radially extending from anouter surface thereof such that compressible material 714 a of the innertube 714 forms the interlock structure for retaining a stent 712. Thecompressible nature of the inner tube 714 allows the stent 712 to bepositioned over and pressed into the inner tube 714 when sheathed by theouter tube 716 thereby preventing axial movement and release of thestent 712. When the outer tube 716 is retracted, the stent 712 expandsand the cells 717 disengage the compressible material 714 a.

FIG. 16B illustrates another embodiment of an inner tube 714′ includingfibers 714 a extending radially therefrom. Fibers 714 a may be straightor hooked fibers in a systematic or random configuration. Stent 712 maybe compressed over the fibers 714 a′ of the inner tube 714′ such thatthe cells 717 capture fibers 714 a therebetween to prevent axialmovement and release of the stent 712 until the outer tube 716 isretracted. Because the stent 712 will be retained throughout its entirelength, the deployment would be more consistent with less of a chance ofelongation or compression.

While the various embodiments of the present invention have related tostents and stent delivery systems, the scope of the present disclosureis not so limited. For example, while particularly suited for stentdelivery systems, it will be appreciated that the various aspects of thepresent invention are also applicable to systems for delivering othertypes of self-expandable implants. By way of non-limiting example, othertypes of self-expanding implants include anastomosis devices, bloodfilters, grafts, vena cava filters, percutaneous valves, or otherdevices. Also, while the interlocks of the present disclosure aredescribed, in embodiments, to be within 5 millimeters of an end of theircorresponding implant to enhance deployment control, larger spacingscould be used for certain applications.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingfigures are non-limiting exemplary embodiments, and that thedescription, disclosure, and figures should be construed merelyexemplary of particular embodiments. It is to be understood, therefore,that the present disclosure is not limited to the precise embodimentsdescribed, and that various other changes and modifications may beeffected by one skilled in the art without departing from the scope orspirit of the disclosure. Additionally, it is envisioned that theelements and features illustrated or described in connection with oneexemplary embodiment may be combined with the elements and features ofanother without departing from the scope of the present disclosure, andthat such modifications and variations are also intended to be includedwithin the scope of the present disclosure. Accordingly, the subjectmatter of the present disclosure is not to be limited by what has beenparticularly shown and described, modifications and equivalents of thedisclosed concepts are intended to be included within the scope of theclaims.

1-15. (canceled)
 16. A stent delivery system comprising: an expandablestent comprising a first interlock structure; an elongated inner memberdefining a longitudinal axis; a floating retaining ring disposed on theinner member and comprising a second interlock structure configured toengage the first interlock structure of the expandable stent, thefloating retaining ring configured to move longitudinally relative tothe inner member; and a sheath mounted on the inner member, the sheathconfigured to be retracted with respect to the expandable stent to atleast partially expose the expandable stent from the sheath.
 17. Thestent delivery system of claim 16, wherein the floating retaining ringis configured to be freely moveable along a longitudinal length of theinner member.
 18. The stent delivery system of claim 16, wherein thefloating retaining ring is configured to be moveable over apredetermined longitudinal length of the inner member.
 19. The stentdelivery system of claim 16, wherein the floating retaining ring is adiscontinuous ring defining free ends at each respective end of thediscontinuous ring.
 20. The stent delivery system of claim 19, whereinthe free ends of the floating retaining ring define a gap therebetween.21. The stent delivery system of claim 19, wherein the free ends of thefloating retaining ring at least partially overlap.
 22. The stentdelivery system of claim 19, wherein the floating retaining ringcomprises separate ring sectors.
 23. The stent delivery system of claim16, wherein the second interlock structure is attached to anintermediate tube disposed between the inner member and the sheath. 24.The stent delivery system of claim 16, wherein the second interlockstructure is attached to the inner member by a flexible structure thatallows the second interlock structure to move a predetermined distancealong the inner member.
 25. The stent delivery system of claim 24,wherein the flexible structure comprises a spring.
 26. The stentdelivery system of claim 16, wherein the expandable stent comprises aself-expanding stent.
 27. The stent delivery system of claim 16, whereinthe expandable stent comprises a balloon expandable stent.
 28. A stentdelivery system, which comprises: an elongated inner member defining alongitudinal axis; an expandable stent mounted about the inner member; agenerally annular retainer mounted to the inner member and dimensionedto releasably couple with the expandable stent, the generally annularretainer dimensioned for longitudinal movement along the inner member;and a sheath mounted on the inner member, the sheath configured to beretracted with respect to the expandable stent to at least partiallyexpose the expandable stent from the sheath.
 29. The stent deliverysystem of claim 28, wherein the generally annular retainer and the stentcomprise cooperating interlocking elements dimensioned to releasablycouple the expandable stent to the generally annular retainer.
 30. Thestent delivery system of claim 28, wherein the stent is configured to beself-expanding, wherein, responsive to movement of the sheath to thedeployed position, the expandable stent is configured to expand andenable release of the stent from the retainer.
 31. The stent deliverysystem of claim 28, wherein the generally annular retainer is adiscontinuous ring defining free ends at each respective end of thediscontinuous ring.
 32. The stent delivery system of claim 31, whereinthe free ends of the discontinuous ring define a gap therebetween. 33.The stent delivery system of claim 31, wherein the free ends of thediscontinuous ring at least partially overlap.
 34. The stent deliverysystem of claim 31, wherein the discontinuous ring comprises separatering sectors.
 35. The stent delivery system of claim 13, wherein theexpandable stent comprises a self-expanding stent.